Though edible items like sugar, tea and coffee are included in the 5% slab, milk does not attract any tax under the new GST regime. The idea behind this is to ensure that basic food items are available for everyone but instant food is kept out of this category.

• Basic household items like toothpaste and hair oil, which currently attract 28% tax, will be taxed at 18% only.
• Sweets will also be taxable at 5%.
• Tax rates on coal has also been reduced from 11.69% to just 5% in order to relieve the pressure on power industries.
• GST also gives a major push to domestic industries as they will be able to procure seamless input credit for capital goods. Make in India campaign is set to flourish after this reform.

GST Rates on Goods

The government has proposed a 4-tier tax structure for all goods and services under the slabs- 5%, 12%, 18% and 28%. After the recent revision of GST rates, these are the commodities that fall under the four tax slabs along with those that do not attract any tax. Please note that only those commodities are included in this list whose rates have been revised in various council meetings.

See you are providing two different supplies that is material and services of installation these two are different services and for same invoices are issued separately so it cannot be considered as mixed supply so in case a notice is issued based on two different services you can contest.

See the supply is not naturally bundled in your case as the client may or may not take services ,also you are not selling it as bundled service so there is good chance to defend the case

If the installation service is not mentioned in packages offered by you or not done on regular basis but occasionally on demand of customers, mixed supply criteria shall not be applicable and gst would be applicable separately for supplies and services.

This would be your defence. 

Where the product supply accompanied with installation is mixed supply, single GST will charge on whole i.e that maximum rate and not separate rates.

IN cases where, installation service not provided, 12%. So this differentiation shall be fill when GST deducted that installation provided or not.

If the applicable gst for installation and product ate different then you can very well issue different gst rates and invouces for the same

Dear

Mixed supply criteria doesn't apply in your case because you are providing sale of product(Goods) and Service of Installation which are two different type of taxable items one is goods and other is services.

You can produce the documents under which you have clearly described the amount collected towards GST and give a reply through your auditor or advocate about this and ge the issue clarified or prefer an appeal.

You are clear in your thoughts that this may not be applicable in your case, hence with the support of documentary evidences, you may prefer to issue a proper reply notice and also take up this with the appellate authority if  your pleas are unheard.